This invention relates to telecommunication networks and, in particular, to switches in an asynchronous transfer mode (ATM) network.
In a telecommunication network, units of data must be routed between different points of the network through switches. In ATM networks, traffic streams of mixed types of information are carried according to the concept of "bandwidth on demand." The data units, ATM cells, are transferred in accordance with the varying requirements of each ATM cell. Data units which are time-critical are given priority in network routing. Data units which are information-critical are given priority against cell loss. This ability to handle video, voice, computer data and other information has led to the wide acceptance of ATM as a prospective network standard.
An ATM network switch must route information reliably with minimum delay and loss, but the wide variation in requirements in ATM networks creates heavy demands upon the ATM switch. Different designs have been proposed and implemented. Manifest shortcomings have included complexity, high cost, and impediments to configuration changes. In many designs the switch is created from complex components which centralize switch operations. Not only are the components expensive, but switch configuration changes are difficult because the centralized operations must also be changed to accommodate the new switch configuration. A far better design is to rely upon modularity by which components can easily be added to, or removed from, the switch.
The present invention solves or substantially mitigates these problems with an ATM switch in which buffering is expeditiously distributed with a backpressure system which maximizes the speedy transmission of time-critical data and minimizes the loss of information-critical data. The ATM switch is modular in construction and fairly low cost components may be used.